W.B.Na.466. iMosd itbraary 1, U12. 

U.S. DEPARTMENT OF AGRICULTURE. 

WEATHER BUREAU. 



GB 1205 

.1)6 

1912 

copy i INSTRUCTIONS TO 

SPECIAL 

RIVER AND RAINFALL OBSERVERS 

OF THE WEATHER BUREAU. 




H. 0. FEANKENFIELD, 

PBOPSSSOE OF METEOEOlOGY. 



Prepared under direction of WILLIS L. MOORE, Chief of Weather Bureau. 




WASHINGTON: 

GOVERNMENT PRINTING OETIOB 

191ft 



W. B. No. 469. Issued February 1, 1912. 

U. S. DEPARTMENT OF AGRICULTURE. 

WEATHER BUREAU. 



INSTRUCTIONS TO 

SPECIAL 

RIVER AND RAINFALL OBSERVERS 

OF THE WEATHER BUREAU. 



BY 

H. C. FRANKENFIELD, 

PROFESSOR OF METEOROLOGY. 



Prepared under direction of WILLIS L. MOORE, Chief of Weather Bureau. 




WASHINGTON: 

GOVERNMENT PRINTING OFFICE. 

1912. 



0* 






NOTE TO SPECIAL RIVER AND RAINFALL OBSERVERS. 



This book of instructions will be carefully preserved. When an 

observer is relieved or is to be temporarily absent from his station he 

will turn it over to his successor, obtaining the latter' s receipt therefor, 

which will be forwarded by mail to the official in charge of the district. 

2 

n m ' 



Y 



INSTRUCTIONS 

FOR 

SPECIAL RIVER AND RAINFALL OBSERVERS. 



OBJECT OF RIVER AND RAINFALL OBSERVATIONS. 

The river and rainfall stations of the Weather Bureau are main- 
tained primarily for the purpose of giving warning of the approach, 
magnitude, and duration of high waters, and for forecasting water 
stages at all heights, in the interest of navigation on the inland water- 
ways of the country. The river and precipitation data are also of 
great value to various other interests, particularly to those concerned 
with the problems of irrigation and water supply. 

DISTRICT CENTERS. 

For the better supervision and control of the work, the special 
stations are arranged in districts. These districts are under the direc- 
tion of officials at regular meteorological stations of the Weather 
Bureau, designated as district centers. The centers are usually at the 
lower end of the districts. 

All correspondence relating to the work of substations, such as the 
furnishing of supplies, renewal of gages, settlement of accounts, and 
employment of observers, is conducted through the official in charge 
at the district center to which the station is assigned. 

Observers are furnished with penalty envelopes for correspondence 
with the district center and with the Central Office at Washington, 
D. C, on matters pertaining to the work of the station. No postage 
is required on penalty envelopes. 

Persons accepting positions as special river and rainfall observers of 
the Weather Bureau become authorized agents of the United States, and 
are amenable to the laws in case of neglect of duty. 

River gages are constructed at the expense of the United States, 
except where permission can be obtained to use those already installed 
by municipalities, counties, townships, or corporations. 

Duplication of gages will be avoided when possible, both in the 
interest of economy and to prevent confusion arising from double 
records of stages. 

The records of stages are preserved at Washington and printed from 
time to time. They are accessible to interested persons at all times. 

3 



4 INSTRUCTIONS TO RIVER AND RAINFALL OBSERVERS. 

SUPPLIES. 

Supplies of blank forms, franked and addressed envelopes, rain 
gages, measuring sticks, and other necessary supplies are furnished 
to observers upon application to the oflicial in charge of the district 
center. Timely requisition will be made for such supplies as are 
needed, and the needs of the station must be so anticipated as to 
allow ample time for the delivery of the articles from the Central 
Office at Washington, D. C, through the district center. One month 
is usually sufficient for this. 

INSTRUCTIONS. 

The duties of a river observer consist in noting on a form furnished 
for the purpose — 

First. The height of water on the gage, with change in 24 hours. 
Second. Depth of rain or melted snow, with times of beginning 

and ending. 
Third. Actual depth of snow, if any, since last observation. 
Fourth. Direction of wind. 
Fifth. State of weather. 

Sixth. Depth of snow, if any, on ground on 15th and last day of 

month; also date on which last snow of season disappeared. 

Seventh. Stage of river at crest of each flood, with hour of day, 

should it not occur at time of regular observation. 

A postal card containing a record of the observations is also mailed 

daily, when required, to the official in charge of the district center. 

A postal card (Form 1049, Met'l) containing the original record of 
the daily stages of water in the river is mailed on the last day of each 
month to the Chief U. S. Weather Bureau, Washington, D. C. 

Telegraphic reports are also made under certain conditions as here- 
inafter set forth. 

The duties of a rainfall observer consist in noting on a form fur- 
nished for the purpose — 

First. The depth of rain or melted snow, with times of beginning 

and ending. 
Second. Actual depth of snow, if any, since .last observation. 
Third. Direction of wind. 
Fourth. State of weather. 

Fifth. Depth of snow, if any, on ground on 15th and last day of 
month. 
A postal card containing a record of the observations is also 
mailed daily, when required, to the official in charge of the district 
center. 

Telegraphic reports are also made under certain conditions, as 
hereinfater set forth. 



INSTRUCTIONS TO RIVER AND RAINFALL OBSERVERS. 5 

AH reports will be rendered to the officials in charge of the district 
centers, who will disseminate the information so as to best subserve 
the interests of the public. 

The height of water on the gage should be noted to the nearest 
tenth of a foot each day, including Sundays and holidays. 

This can only be done accurately when the water is placid; in a 
rough or turbulent stream* or when there is much wind, the waves 
prevent accurate readings. In such cases the tenths must be esti- 
mated as near as possible by taking the average of the highest and 
lowest marks on the gage which the water is seen to touch. 

The depth of rain or of melted snow, or of melted snow and rain, 
must be given in inches and hundredths of an inch, properly separated 
by a decimal point. 

A measurement of the actual depth of the snowfall since last obser- 
vation must always be made and entered in inches and tenths of an 
inch. 

In addition to measuring the depth of snowfall since the last obser- 
vation, a measurement should be made of the actual depth in inches 
and tenths of an inch of the accumulated snow on the ground at the 
time of the observation on the 15th and last day of the month. 

It is desired, if it can be readily determined, that the observer report 
in the space on the form prepared for that purpose, the date on which 
the last snow of the season disappeared. 

Full instructions as to the methods to be used to obtain the above 
data will be found under the head of "To measure rainfall or snow 
fall." 

The direction of wind will be designated by the eight principal 
points of the compass, viz: N., NE., E., SE., S., SW., W., and NW., 
legibly written. When there is no wind, the word "Calm" should be 
recorded. 

The state of weather will be determined and recorded with reference 
to the degree of cloudiness, and whether or not precipitation is falling 
or likely to fall soon ; thus when the sky is three-tenths or less covered 
with clouds, record "Clear;" four to seven-tenths, inclusive, "Partly 
cloudy;" eight to ten-tenths, "Cloudy;" and "Sprinkling," "Light 
rain," "Heavy rain," "Light snow," "Heavy snow," "Sleeting," 
"Hailing," "Threatening," "Clearing," when these conditions exist. 
When light fog, light haze, or light smoke is observed with no clouds, 
the state of the weather will be recorded as "Clear." 

Any ususual occurrences connected with the stages of the water in 
the river, such as the presence of floating ice or timber, the formation 
and breaking up of ice gorges and other obstructions should be noted. 
Thunderstorms, hailstorms, tornadoes, and earthquakes will also be 
recorded. 



6 INSTRUCTIONS TO RIVER AND RAINFALL OBSERVERS. 

Observers should, when possible, have substitutes capable of per- 
forming all the duties of a river observer, in order that there may be 
no interruption of the work in case of sickness or unavoidable absence 
from the station on the part of the regular observer. Members of the 
observers' families are very often instructed in the work. 

TIME OF OBSERVATION. 

The observation of the river stage will be made daily at 8 a. m., 75th 
meridian time, except when otherwise directed. 

In all cases the 75th meridian time of observation should be given in 
the proper space at the head of the form, whether 8 a. m. or some 
other time. 

The observations in feet and tenths of a foot will be written in the 
fiist column of the monthly blank form. 

When the stage is below the zero of the gage it will be written in 
the form with a minus ( — ) sign before it. 

The rise or fall will be given in the proper column on the form in 
feet and tenths of a foot. When the change is a fall it should have 
the minus ( — ) sign placed before it. 

SPECIAL OBSERVATIONS. 

Special observations of the stage of water will be made at other 
times of the day than 8 a. m. when requested by the official in charge 
of a district center or by the Central Office in Washington, or when 
the river is near, at, or above the flood stage. 

It is desirable to have a special observation of the highest stage 
reached by the water jn the case of the very great rises, without any 
request from a district center. In many cases the stage in a rise will 
reach in the course of the day several feet above the 8 a. m. stage and 
fall several feet before the time of the next regular observation on 
the day following. 

When the rise in a river is very sudden and great, and, in the judg- 
ment of the observer, dangerous to points below, the stage will be tele- 
graphed to the district center and to the places most interested in the 
information, according to such special instructions as may be given to 
each observer. 

Special observations will contain exactly the same information as a 
regular report, but the rainfall after being measured should not be 
emptied out of the gage, but left therein until the next regular obser- 
vation, when, after measuring, it will be poured out. 

RIVER GAGE.. 

A river stage is the vertical height of the water surface in feet above 
some definite plane, the zero of the gage usually, at, or somewhere 
near, the level of the lowest water that has occurred. A river gage is 
a device for observing the river stage. 



INSTRUCTIONS TO RIVER AND RAINFALL OBSERVERS. 7 

When possible without too great expense, river gages are made ver- 
tical. They ordinarily consist of a plank or planks, usually 2 inches 
thick and 8 to 12 inches wide, fastened to a bridge pier or piling or 
other structure, and of sufficient length to cover the greatest range in 
height of water ever likely to occur. The planks are graduated to feet 
and tenths, and the height of the surface of the water in the river can 
be read on it by estimation to the nearest tenth of a foot. 

Sometimes river gages consist of a strip of the surface of a stone pier 
dressed smooth so as to receive the necessary marking and numbering. 

When a river gage can not be set vertically, it is laid along the 
bank according to the slope of the ground. It should then be made 
of heavy timbers, at least 6 by 6 inches, and preferably of oak, hard 
pine, or Oregon fir, embedded in the ground, with the top surface 
even with the surface of the ground on the river bank. Strap iron 
£ inch thick and 2 inches wide, is spiked along the top and upstream 
sides, and on the toppiece are cut the foot and intermediate marks. 
The even foot marks are also indicated by figures, in brass or paint, 
on the timber. The foot marks on a gage of this kind must be accu- 
rately located by a' civil engineer. 

Very substantial inclined gages are made of concrete or lengths 
of block stone, with bars of railroad iron inlaid, on which the foot 
marks are cut. 

It is not always possible at the time of setting a gage to put the 
zero of graduation at the exact level of the lowest water apt to occur, 
or the lowest that has occurred in a long period of years. In such 
cases the gage should be finished as far down as possible, and com- 
pleted when the water falls sufficiently low. 

When a stage of water below the zero occurs it is read as a minus 
stage. It is desirable that the zero should be put so low that this will 
never occur, as the minus sign is apt to lead to confusion. The bed 
of the river channel usually makes the best zero mark. 

When a gage is once established and a long record of readings made, 
it is not advisable to make any change in its zero on any pretext 
whatever, even if a stage lower than any ever before known should 
occur. 

For the purpose of ascertaining from time to time *iiy changes that 
may occur in the level of the zero of a gage or any of its marks, a 
bench mark should be established close by the gage or somewhere in 
its vicinity. A bench mark consists of some accessible, presumably 
permanent, point or surface, the difference in level between which and 
the zero or some other mark on the gage is known by actual leveling 
between the two. When this difference is found to vary it is presumed 
it indicates a corresponding change in the level of the marks of the 
gage, requiring either adjustment of the gage or correction of its 
readings. 



8 



INSTRUCTIONS TO RIVER AND RAINFALL OBSERVERS. 



A bench mark is essential in case a river gage is to be repaired or 
renewed, in order that the new gage may be set at exactly the same 
level as it was before. On a bridge pier the top surface of the largest 
stone accessible in the top course of masonry is often used as a bench 
mark. Sometimes a bench mark is the top surface of a large stone 
buried in the ground specially for the purpose of estab- 
lishing a permanent surface. Prominent surfaces in 
stone buildings are good places for permanent bench 
marks. A copper bolt, or metal plate, set in the stone 
wall of some public building, such as the customhouse, 
post office, or city hall, is a common device for a bench 
mark in a large city. 

The river gages used by the Weather Bureau are 
partly shown in figures 1, 2, 3, and 4. The design best 
adapted to any particular location will be used in each 
case. 

The specifications to be followed in procuring bids for 
the construction of these gages are as follows : 



3 



7 



£ 



4 



3 



2 



6 



u 



Fig. 1. 



SPECIFICATIONS FOR RIVER GAGE SHOWN IN FIG. 1. 



The river gage will be made of sound pine or oak 
timber, free from knots or shakes, 2 inches in thick- 
ness, 12 inches in width, and of such a length as to 
extend, if possible, from 2 or more feet below the zero 
point to about 5 feet above the highest known water. 
The face of the plank upon which the graduations are 
to be made, and the top, bottom, and sides, will be 
planed smooth, and will receive two coats of the best 
white-lead paint. The face will then be graduated as 
follows : 

Commencing at the point which will correspond to the 
zero, graduate the gage both above and below that point 
in feet and tenths of feet. 

The graduations will be chiseled or burnt into the 
wood to the depth of about one-eighth of an inch and 
ttyen given two coats of the best black paint. The 
marks for whole feet will extend entirely across the face 
of the gage; those for half-feet one-half the distance 
across, beginning on the left side, and those for the 
intermediate graduations one-fourth of the distance 
across, beginning on the left side. Whole feet will also be shown by 
the appropriate figures, 6 inches in height, on the right side of the 
gage, and so placed that the marks for whole feet will exactly bisect 
the figures. The figures will also be chiseled or burnt into the wood 
to the depth of about one-eighth of an inch, and then given two coats 



INSTRUCTIONS TO RIVER AND RAINFALL OBSERVERS. 



9 



of the best black paint. The legend, U. S. Weather Bureau, should 
be painted in black across the top of the gage. 

Having graduated the gage, select a pile or other stationary object 
on some portion of the levee, wharf, or bank where the gage will be 
secure from injury. Lower the gage into the water, talcing care to 
keep it in a vertical position until it touches the bed of the river or 
its zero is the point of lowest water; then securely fasten it by spikes 
or bolts. 

SPECIFICATIONS FOR RIVER GAGE SHOWN IN FIG. 2. 

Procure a piece of pine, cypress, or oak timber about 6 by 6 inches, 
and of sufficient length to cover the full range of the river between 
extreme low and high water marks. This timber will be placed in 

4 fee t 




Jjjct.LowWater'. S^J> ,< 



Fig. 2. 

the river bank, firmly embedded in the earth, leaving \\ inches 
exposed above the level of the ground. 

To secure this form of gage thoroughly it will be necessary to 
attach it to 4 by 6 or 6 by 6 inch oak, cedar, locust, or fir posts, driven 
6 feet into the ground, and placed 6 feet apart. The upper edge of 
the gage should be planed smooth, and a strap of iron, \ by 2 inches 
screwed along the top on the upstream side, and graduated in feet 
and tenths of feet, after being placed in position, taking the point of 
lowest water, or that which has been selected as the zero of the scale, 
and locating the feet and tenths both above and below that point. 
The graduations for this gage will be the same as for the gage shown 
in figure 1. Especial pains should be taken in graduating the gage to 
see that the distances marked off upon it for each foot and its subdi- 
visions correspond exactly to a vertical foot and its subdivisions of 
which it is a measure. This should be done by means of an ordinary 
carpenter's square and a spirit level. 
28392—12 2 



10 



INSTRUCTIONS TO RIVER AND RAINFALL OBSERVERS. 



It is also very desirable that this form of gage should have its top 
surface covered with two coats of the best white lead or zinc paint, 
with the proper figures opposite the even footmarks on the iron strap 
in black paint and not less than 4 inches in length. Figures should 
also be burnt in before painting, as permanent markings are thereby 
secured. 




Fig. 3. 
SPECIFICATIONS FOR RIVER GAGE SHOWN IN FIGURE 3. 

Where a stone pier or abutment is available, a very durable gage 
can be made by dressing a face, 12 inches in width, from extreme low 
water to as far above as may be necessary. The dressed surface 
should be covered with two coats of the best black paint, preferably 



INSTRUCTIONS TO RIVER AND RAINFALL OBSERVERS. 11 

asphaltum, after all holes and indentations in the pier have been 
filled with cement. 

The space, both above and below the point at which the zero will 
be placed, will be graduated with two coats of the best white lead or 
zinc paint into feet and tenths of feet. Markings for whole feet will 
extend entirely across the gage; those for half feet one-half the way 
across, beginning on the left side; and those for the intermediate 
graduations one-quarter of the way across, beginning on the left 
side. All markings will be one-quarter of an inch in width. The 
figures for the whole footmarks will be in white, 5 inches in height; 
and the center of each figure must be over the foot fine at the right. 

SPECIFICATIONS FOR THE CONSTRUCTION AND INSTAL- 
LATION OF GAGE BOXES FOR CHAIN AND WEIGHT 
RIVER GAGES. 

(United States Geological Survey pattern.) 

The material, except lumber and paint and heavy bolts, will be 
furnished b}^ the Weather Bureau. 

The box will be made of f-inch oak, cypress, or hard pine lumber, 
planed smooth on both sides, and free from knots and shakes. It 
will be 15 feet in length, 6 inches in width at the bottom (inside 
measurement), 6 inches in height on one side and 4 inches on the 
other. The top will be fastened to the 4-inch side by 6-inch hinges, 
the hinges being secured by l|-inch tire bolts and clamped inside the 
box with washers and nuts. The hinges will be placed one at each 
end of the box and also at intervals of 3 feet, making 6 hinges in all. 
They will be bent around the bottom of the box so that the lower 
screw bolt of each can be driven into the box from the underside. 
A hasp and staple will be attached about 3 feet from each end of 
the box in the usual manner, using IJ-inch tire bolts. The locks 
will be attached with staples or clamps that can be clinched inside 
the box. 

The pulley will be mounted on the 6-inch side of the box, as shown 
in diagram attached, and directly below it the bottom of the box will 
be sawed out. 

A slot one-half inch in depth and width will be cut in the middle 
of the top of the end of the box nearest the pulley. When not in 
use, the weight can then be drawn up, lifted over the end, and placed 
in the box, with the chain in the slot. This will admit of the box 
being securely locked, leaving onry a few inches of chain exposed. 

The scale will be graduated in feet and tenths of a foot on the 
6-inch side of the box (inside), beginning at the inner edge of the 
pulley frame and ending at the far end of the box. The whole feet 
will be marked with 2-inch staples, half-foot marks with 1-inch 
staples, and intermediate graduations with $-inch staples. One 
staple will be used at each foot and half-foot mark and intermediate 



12 



INSTRUCTIONS TO RIVER AND RAINFALL OBSERVERS. 



graduation. The brass figures for the whole feet will then be screwed 

to the bottom of the box. The scale limits of each will be furnished 

by the official in charge of the 
district center. A hook will be 
provided at the far end of the 
box to hold the ring secured to 
the end of the chain. 

When the zero shall have been 
established, the weight will be 
lowered so that its bottom just 
touches the zero point. The 
link of the chain directly op- 
posite the zero mark on the scale 
will then have a rivet driven 
into it and flattened on both 
sides so that it will remain firm. 
Should it be necessary to record 
river readings beyond the scale 
limits of the box, the rivet in the 
chain will be drawn up so that it 
will be exactly opposite the 
highest footmark on the scale. 
Another rivet will then be driven 
into that link of the chain ex- 
actly opposite the zero mark on 
the scale, and readings taken, 
using this second rivet as a 
base. A third rivet can also be 
added if necessary. In record- 
ing readings which are beyond 
the scale limits of the box the 
second rivet will be used as a 
zero mark instead of the first, 
and there will be added to the 
observed reading the distance 
between the rivets, which will 
correspond to the highest read- 
ing on the scale. 

The box will be securely at- 
tached by its 6-inch side to the 
guard rail or side of bridge, the 
former preferred. 

The whole box will be painted 

with two coats of best white lead or zinc paint. 

In making requisition for material for these gages officials in charge 

of river districts will state the length of sash chain required. 













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INSTRUCTIONS TO RIVER AND RAINFALL OBSERVERS. 13 

DESCRIPTION OF THE MOTT RIVER GAGE. 

Box. — The gage box and doors are constructed of sand-dried oak 
lumber dressed on all surfaces, f-inch stock, and inside dimensions as 
follows: Height, 18 inches; width, 18 inches; depth, 1\ inches. 

Doors.— The box has two doors secured with extension hinges in 
such manner as to permit the doors to swing back against the sides of 
the galvanized-iron box. The entire outside surface of the box, 
excepting the bottom, and including the doors, is covered with No. 24 
galvanized iron. The joints of the galvanized-iron cover are lapped 
and soldered, making the cover water-tight. The galvanized-iron 
cover of the box is painted with two coats of dark-green mineral 
paint, with a label on the doors of the box bearing the words "Prop- 
erty United States Weather Bureau. Penalty for Interference." 

Lock. — The box is fitted with a brass mortise lock, using the same 
key as is used in the standard padlock for the chain and weight gages 
of the United States Weather Bureau and United States Geological 
Survey. 

Mechanism. — The box is fitted with a tape reel consisting of an 
aluminum brake wheel and a brass spider, mounted on a turned cast- 
iron standard and fitted with a wooden handle. A leather brake strap 
and suitable levers for releasing the brake are provided. The brake 
strap is attached to a brass coil spring of sufficient strength to hold 
the weight and tape in any position. An iron guide wheel running 
on a turned axle, secured in the box by a cast-iron standard, is also 
provided. 

Tape and gage. — The tape is made of phosphor bronze, gV inch in 
thickness and \ inch in width. It is nickeled throughout, excepting 
the relief in which the figures are etched, which is plain. The tape, 
accurately subdivided to feet, with foot marks numbered consecu- 
tively between such limits as may be necessary, is furnished with each 
gage. A 1-foot scale divided into 100 parts, and having every fifth 
division mark suitably numbered, is placed in the box so as to stand 
cornerwise back of the tape in a vertical position. This scale is made 
of No. 16 gage iron, enameled in black and white with six coats of 
enamel, and is attached to an iron bar which projects upward through 
the top of the box, the projecting end being covered by a cast-iron cap 
or cover attached to the box by screws, the object being to provide a 
suitable bench or reference mark outside the box. 

The 1-foot scale is adjustable vertically. A standard weight of the 
pattern used by the United States Weather Bureau and the United 
States Geological Survey is provided with each gage, together with 
a clip and wire for attaching the same to the tape. The gage weight 
is painted with two coats of white enamel paint. 

Miscellaneous. — Each gage contains a covered compartment for the 
observer's record card, etc., instructions for erecting a gage in various 



14 INSTRUCTIONS TO RIVER, AND RAINFALL OBSERVERS. 

positions, for attaching the weight, checking the gage datum, and 
operating the gage. 

A rectangular wooden down spout, 16 inches in length, with screw 
for attaching the same, is provided with each gage. 

Each gage is also provided with a screw driver and a f-inch twist 
drill for use in erecting the gage. 

Operation. — Release brake and slowly unwind tape until weight 
reaches water. Do not run tape all out without holding reel handle. 
Brake will hold reel in position, and observer can stand to one side to 
see that tip of weight just touches water. Read number of whole feet 
on bronze tape and tenths of a foot on enameled scale. The figure on 
the tape standing opposite some part of the 1-foot scale gives the 
whole feet ; the number of tenths and hundredths on the 1-foot scale 
opposite the index of the number on the tape gives the decimal or 
fractional portion of the gage reading. 

For example, if the number 7 on the tape stands opposite 60 on the 
enameled scale, the gage reading would be 7.6 feet. 

Erection. — The gage may be bolted to the handrail of a bridge, if 
not liable to interference, one side being fastened to tiebars that 
extend down to the floor of the bridge. It may also be secured to a 
platform extending beyond the handrail, the bottom of the box being 
on a level with the top of the rail. When there is no handrail, as on 
most railroad bridges, the gage may be bolted or secured to vertical 
bridge members, or it may stand on horizontal bridge chords, or be 
attached to two sleepers at their ends. In all cases room must be 
provided for the unobstructed movement of the weight. 

Mott gages ready for installation will be supplied from the Central 
Office at Washington, D. C, and bids for installation only will be 
necessary. 

In each instance the exact distance from the zero stage of the water 
to the bottom of the gage box when in position must be furnished. 

RAIN GAGE. 

EXPOSURE OP RAIN GAGE. 

The exposure of the rain gage is a very important matter. The 
most serious disturbing effect in collecting rainfall is the wind. In 
blowing against the gage the eddies of wind formed at the top and 
about the mouth of the gage carry the rain away, so that too little 
is caught. 

Observers will take particular care in selecting a good place for the 
location of a gage, as the value of the records is sometimes greatly 
impaired by improper exposure. It is scarcely necessary to say that 
every precaution should be taken to protect gages from the interfer- 
ence of animals and unauthorized persons. Select, if possible, a 
position in some open lot as unobstructed as possible by trees, build- 



INSTRUCTIONS TO EIVER AND RAINFALL OBSERVERS. 15 

ings, or fences. Such a place in general affords the best exposure. 
Gages should be exposed upon roofs of buildings only when necessary, 
and then the roof should be flat, or nearly so. The middle portion of 
a flat unobstructed roof generally gives the best results. 

Rain gages in slightly different positions differ greatly in the depth 
of rain indicated. Within a few yards of each other two gages may 
show a difference of 20 per cent in the rainfall in a heavy rainstorm. 
The stronger the wind the greater the difference is apt to be. In a 
high location eddies of wind produced by walls of buildings divert 
rain that would otherwise fall in the gage. A gage near the edge of 
the roof, on the windward side of a building, shows a less rainfall 
than one in the center of the roof. The vertical ascending current 
alongside of the wall extends slightly above the level of the roof, and 
part of the rain is carried away from the gage. In the center of a 
large flat roof, at least 60 feet square, the rainfall collected by a gage 
does not differ materially from what is collected at the level of the 
ground. A rain gage mounted on a mast at the height of 43 feet col- 
lects only 0.75 as much as at the ground; at 85 feet, only 0.64; and at 
194 feet, only 0.58. A gage on a plain with a fence 3 feet high around 
it at a distance of 3 feet will collect 6 per cent more rain than without 
the fence. These differences are due entirely to wind currents. 

INSTRUCTIONS FOR THE USB OF THE RAIN GAGE. 

Description of gage. — The rain gage consists of the following parts: 
The receiver A; the overflow attachment B; the measuring tube G. 

The top cylindrical portion of the receiver, marked a in figure 5, is 
exactly 8 inches in diameter, inside, and is provided with a funnel- 
shaped bottom, which conducts any precipitation falling into the 
receiver into the tall cylindrical measuring tube C, the total height of 
which, inside, is exactly 20 inches. The diameter of this tube is much 
smaller than the large receiving tube a, being only 2.53 inches. In 
consequence of this a small amount of rain falling into the receiver 
and flowing into C fills the latter to a depth greater than the actual 
rainfall in proportion as the area of the receiver is greater than the 
area of the measuring tube. In the standard gages of the Weather 
Bureau the depth of the rainfall, in accordance with this principle, is 
magnified just 10 times. The receiver A has a sleeve d, figure 5, 
which slips over the tube C, and very effectually prevents any loss of 
rainfall. Again, when the rainfall is very heavy the tube C may be 
more than filled. In this case, to still prevent loss, a little opening, 
shown at e, figure 5, is made in the sleeve d, just on a level with the 
top of the tube C. 

The excess of rainfall escapes through this opening, and is retained 
in the large overflow attachment B, and can be measured afterwards, 
as will be described below. The diameter of the overflow attachment 



16 



INSTRUCTIONS TO RIVER AND RAINFALL OBSERVERS. 



in the latest style gages is now made just 8 inches inside diameter. 
The object of this is to be able to use this portion of the instrument as 
a snow gage, as will be explained hereinafter. 



RAIN GAGE AND SUPPORT. 



The box in which the gage is shipped to the observer is expressly 
designed as a stand for the instrument, and should be opened at the 
head, which is fastened by screws. Set the box up as nearly vertical 
as possible at the place selected for the exposure, and secure it in this 
position by driving down four stakes alongside, in the manner indi- 
cated in figure 6. Care must be taken to have the gage in a truly ver- 



I'ront View. 



Vertical Section. 




Horizontal Section, EJl 



O 12 3 4 5 6 7 8 3 10 H IB 13 14 IS .16 17 /8 19 BO Bl BB B3 B4 t/tCHSS 



SCALE. 

Fig. 5.— Rain gage. 

tical position. Slip in the head and lower it to the level of the screw 
holes in the sides of the box about 10 inches from the bottom, where 
the head will be securely fastened with the screws taken out in opening 
the box. The gage can now be placed inside, and appears as shown 
in figure 6. 

TO MEASURE RAINFALL AND SNOWFALL. 

RAINFALL. 

The rain-gage measuring stick is graduated into inches and tenths 
of inches. Remembering that the actual depth of the rainfall is mag- 
nified 10 times, as explained above, it is plain that if we find the water 



INSTRUCTIONS TO MVER AND RAINFALL OBSERVERS. 



17 



10 inches deep in the measuring tube the real rainfall must have 
been only 1 inch deep; or if the water in the tube is only one- 
tenth inch (or, written as a decimal, 0.1 inch deep) the rainfall 
must have been only one one-hundredth inch (or, written as a deci- 
mal, 0.01 inch). 

To save observers the trouble of always .thinking about the mag- 
nification, and to avoid possible errors in reports, the numbers on 
the graduations of the measuring sticks are not actual inches, but 
have all been divided by 10, and thus represent the actual rainfall. 
Moreover, these numbers are expressed in hundredths of inches of 
rainfall, and are written as decimal fractions. Thus the 10-inch 
line is numbered 1.00 (read one and zero 
hundredths), which is the depth of rain- 
fall in inches corresponding to 10 inches 
of water in the measuring tube: simi- 
larly the 1-inch line is numbered 0.10 
(read ten one-hundredths) , which again 
is the depth of rainfall in inches cor- 
responding to 1 inch of water in the 
tube. 

The depth of the water is measured by 
inserting the measuring stick into the 
gage through the small hole in the fun- 
nel. When the stick reaches the bottom 
of the measuring tube it should be held 
for one or two seconds and then quickly 
withdrawn and examined to see at what 
division of the graduation the top of the 
wetted portion comes. The numbering 
of this division, as stamped on the stick, 
gives, as has just been explained, the 
actual depth of rainfall, and in making- 
out records and reports observers should 
always use the decimal expressions. Of 
course, it will rarely happen that the top of the wetted portion will 
fall exactly upon one of the numbered lines — it will generally be on 
or near one of the shortest lines. Thus, for example, suppose the 
watermark comes to the sixth short line beyond the line numbered 
0.80, the proper record to make in this case would be 0.86-inch rain- 
fall. The number of short lines, reckoned from the numbered line 
next lower, are alwaj^s to be inserted in place of the in the 
stamped numbers. 




Fig. 6.— Rain gage and support. 



18 INSTRUCTIONS TO RIVER AND RAINFALL OBSERVERS. 

Observers should always be careful to put the stick into the gage 
so that the end at which the numbering begins goes to the bottom, 
and the stick passes through the middle of the tube; for if the stick is 
placed near the sides the water is sometimes drawn up by capillary 
action into the narrow space between the stick and the tube so as to 
wet the former entirely too high and give very erroneous records. 

After measuring and recording in this way the precipitation found 
in the gage the top should be removed, the measuring tube emptied 
and drained, and the gage put in position again. Observers should be 
careful after emptying the gage to replace the measuring tube so that 
the bottom stands within the ring in the middle of the bottom of the 
overflow, and in putting on the receiver to see that it passes over the 
measuring tube and rests squarely down upon the overflow. 

When the amount of rain that has fallen more than fills the measur- 
ing tube, some care is required to determine the total rainfall. First , 
carefully remove the receiver so as not to spill any of the water in the 
measuring tube, which should be exactly full. If some water has 
been slopped out and the measuring tube is not exactly full, the 
amount of water remaining must be accurately measured with the 
stick as already described. The tube is then lifted out slowly and 
carefully, if full, so as not to spill any of the water into the overflow, 
emptied, and allowed to drain a moment or so. The water remaining 
in the overflow is then poured into the measuring tube, care being 
taken not to lose any, and measured in the usual way. Suppose this 
is found to be 0.47 inch rainfall, then, remembering that the measur- 
ing tube is just 20 inches high, the total rainfall will be 2 inches plus 
0.47 inch=2.47 inches. Or, in case some water was spilled from the 
measuring tube, the 0.47 inch should be simply added to the first 
measured amount to give the total rainfall. 

SNOWFALL. 

During the winter season, especially in those climates where the 
precipitation is nearly all in the form of snow, only the overflow 
attachment will be exposed in the support as a snow gage, removing 
the receiver and measuring tube to the house. These parts can not 
be used for measuring snow, and even if rain should occur it would 
be very apt to freeze and injure the measuring tube. 

When the overflow collector is unprotected from the wind its catch 
represents the true amount of snow only in the case of precipitation 
during calms or very light winds. On windy occasions the catch is 
often highly inaccurate and in the absence of special appliances such 
as described in the Appendix, the true quantity must be found, if 
possible, by measuring a section of the freshly fallen snow cut out 
by forcing the overflow, mouth downward, through the layer and then 



INSTRUCTIONS TO EIVER AND RAINFALL OBSERVERS. 19 

slipping a thin board or sheet of metal underneath so as to separate 
and lift up the section of snow thus cut out. 

Assuming that a representative quantity of snow has been obtained 
in the overflow, a measurement may be secured by placing the vessel in 
a warm room until the snow has melted and then measuring the water 
in the measuring tube in the usual way. 

The method just described is objectionable, owing to the time 
required and to the loss of the snow or water by evaporation. The 
following plan is much better: Take the overflow into the room and 
pour into it one measuring tube full of water to the brim, preferably 
warm. In cases of deep snowfall more water will be required. This 
will melt, or at least reduce to a fluid slush, a considerable amount of 
snow. The measuring tube should then be filled to the brim from 
the melted contents of the overflow and emptied; thereby discarding 
a quantity of water equal to that added. The remaining water in 
the overflow, when measured in the tube, then gives the actual depth 
of melted snow. 

In addition to this measurement by the gage a measurement will 
be made of the actual depth in inches of the snow on the ground. 
Select a level place of some extent, where the drifting is least pro- 
nounced, and measure the snow in at least three places. The mean 
of these measurements will give the snowfall, which is to be entered 
in the column of the report headed "depth of snowfall in inches." 
Whenever it is impracticable to melt the snow as described in the pre- 
ceding paragraph, one-tenth of this mean will give an approximate 
value, in water, for the snow which could not be melted. This value 
must be set down in the proper column of the report in precisely the 
same manner as rainfall or snow melted in the gage. After snowfall 
has once been measured the same snow should not be measured at 
subsequent observations. Any fresh snow, however, should be 
measured and recorded as it falls. For additional instructions for 
measuring snow see detailed description of methods and apparatus 
in Appendix, Circular E, Instrument Division, third edition. 

Observations of rainfall should be made at the time of river observa- 
tions, and the gage should be emptied of all the water it may contain 
as soon as it has been measured. 

If no rain, snow, or hail has fallen during the period of observation, 
make the entry ".00" in the proper column. If the amount is too 
small to measure, make the entry "Trace" or "T." 

It is particularly important in the interest of accuracy that the 
observations be recorded as soon as made and that the daily entries 
be made each day. Even if no rain has fallen, the observer should 
bear in mind that his official record of that fact is very important. 

Snow-cutting tubes and scales. — The type of measuring apparatus 
now to be described, and illustrated in figure 7, is designed to secure 



20 INSTRUCTIONS TO RIVER AND RAINFALL OBSERVERS. 

accurate observations of the depth and water contents of the whole 
layer of snow on the ground. 

These data are of great practical value in all problems of hydrology, 
especially at the close of winter seasons and the general breaking up 
of icebound conditions. 




Figure 7.— Snow-cutting tubes and scales. 

The tubes are made of galvanized sheet iron; they are about 2| 
inches in diameter, and are of greater or less length, according to 
climatic conditions of different sections. For the great majority of 
stations in the United States, tubes 50 inches long meet every ordinary 
requirement, but long tubes and sectional tubes are needed for proper 
measurement of deep beds of snow, such as are found in the western 



INSTRUCTIONS TO RIVER AND RAINFALL OBSERVERS. 21 

mountains. One end of the galvanized tube is reenforced by a piece 
of seamless steel tubing, 6 or 8 inches long and of smaller diameter, 
which is forced tightly inside the galvanized tube, the two being 
securely riveted together. The slightly projecting end of the steel 
tube is coarsely serrated with keenly cutting teeth to facilitate 
perforating icy incrustations, or ice itself in the snow beds. . 

The outside of the tube may be provided with a scale of inches 
which for permanence and accuracy is engraved on a separate piece of 
metal tape (brass, dull nickel finish) fastened to the tube. A ring 
secured to the side of the tube permits it to be attached to an appro- 
priate spring balance for weighing. The dial of the balance is gradu- 
ated and figured to show the water equivalent of the contents of the 
tube. The whole dial represents 10 inches of rainfall, with subdivi- 
sions to inches and tenths. As the individual spaces are about f inch, 
estimations to hundredths can be made, if this order of accuracy is 
considered necessary. 

The tubes are decidedly the best means to employ in measuring 
deep beds of snow, but other methods are better for thin layers of 
freshly fallen snow. The proper tare allowance for the empty tube 
must generally be determined and applied to readings. 

It may be well to remark here that, in case of measuring snow 
layers of small thickness with the tubes, better and more accurate 
average values can be obtained by cutting out two or possibly three 
sections at different points and collecting and weighing all of them in 
the tube at once. The observed net weight must of course be divided 
by the number of samples taken. 

Snow-cutting tubes and scales are described here for the general 
information of Eiver Observers, but the instruments are furnished 
only in special cases. For full particulars concerning methods of 
snow-fall measurement, observers should consult Weather Bureau 
Circular E, Instrument Division, third edition. 

RECORDING OBSERVATIONS. 

Form 1006, Met'l. — The record of the observations made at the 
station for the month, and should be filled up in accordance with the 
instructions printed on the back of the form. 

The form should be mailed to the official in charge of the district 
center on the first day of the succeeding month. 

Before mailing, a copy must be made by the observer in the book 
furnished for that purpose. 

Form 302/f., Tel. — For telegraphing reports in accordance with 
instructions hereinafter given. 

Form 1084, Met'l {postal card). — For reporting the daily observa- 
tions to the official in charge of district center or to other officials 
when specially authorized. 



22 INSTRUCTIONS TO RIVER AND RAINFALL OBSERVERS. 

Form 1049, Met'l (postal card). — For reporting the record of the 

stage of water in the river for the month, to the Chief United States 

Weather Bureau, Washington, D. C. This is the original record of 

river stages. 

PROPERTY. 

When property and supplies are furnished to an observer, an item- 
ized receipt therefor will be immediately mailed to the official in 
charge of the district. 

When an observer is relieved from charge of a station, he will make 
out a list in triplicate of all Government property in his possession, 
and append at the bottom thereof the following certificate: 

(Date) , 19—. 

I certify that I have this day received from -* (name of former observer) 

the above-mentioned articles in good condition unless otherwise specified hereon. 

(Name of new observer) . 

One copy of this report will be mailed to the official in charge of the 
district, one given to the new observer, and the third retained by the 
retiring observer. 

When from any cause any article of property becomes unserviceable 
or in need of repairs, the fact must be at once communicated to the 
official in charge of the district for such action as he may deem proper 
and necessary. 

The Chief of the Weather Bureau reserves the right to withhold 
payment from any person who persistently neglects to make his 
reports accurately and forward them promptly. Payment will be 
made quarterly. 

REPORTS, WHEN TELEGRAPHED. 

Some river observers, when specially instructed, telegraph daily 
stages to the district center, others only when the river reaches a cer- 
tain height on the gage, and still others when the water is near, at, 
or above the flood stage. 

In all cases, however, when the rainfall in the preceding twenty- 
four hours equals or exceeds 1 inch (or less in special cases), the 
observer will take a reading of the river gage and telegraph it, together 
with the amount of precipitation, direction of wind, and state of 
weather at the time of observation, to the official in charge of the 
district center. 

Telegrams concerning the formation or breaking up of ice gorges, 
of heavy drift, or other obstructions in the river, when of sufficient 
extent to endanger navigation or destroy property, will be sent to the 
district centers and places specially authorized. The telegrams 
should give, in as few words as possible, the location and extent of 
the dam or obstruction. 



INSTRUCTIONS TO RIVER AND RAINFALL OBSERVERS. 23 

Observers will not prepay telegrams on official business, as settle- 
ment will be made by the Washington Central Office direct with the 
telegraph companies sending the reports. 

TELEGRAPHING REPORTS. 

Telegraphic reports will contain the fullest information possible 
within a limit of twenty words, including the address and signature. 

Reports for telegraphic transmission will be written on Form 
3024 Tel., in the following order: First, the word "observer"; sec- 
ond, name of the place to which the report is to be telegraphed; 
third, name of station from which report is telegraphed; fourth, time 
of observation if other than 8 a. m., 75th meridian time; fifth, state of 
weather; sixth, stage of river; seventh, a word to indicate the action 
of the water, as "rising," "falling," or "stationary," as the case may 
be; eighth, depth of rainfall; ninth, depth of unmelted snow in 
inches; tenth, surname of observer sending the report. 

Reports of regular observations taken at 8 a. m., 75th meridian 
time, need not contain the time of observation. If no rain or snow 
has fallen since last observation, and there is no snow on the ground, 
no mention need be made of the fact in the telegraphic report. The 
direction of the wind will not be sent, unless specially called *for by 
the official in charge of the district center. 

The rising or falling feature of a river is especially important at the 
high stages when the crest of a flood wave is approaching. Should 
the river become frozen, the information will be included in the 
telegraphic report. 

The reports should be carefully and legibly written in letters that 
can not be misunderstood. Observers are advised to write messages, 
whenever possible, in print letters instead of a running hand. Care 
should be taken to so make the script or running hand letters that an 
"o" may not be mistaken for an "a," a "t" for an "1," an "i" for 
an "e," and so on. The actual stage of the river in feet and tenths 
of a foot will be spelled out, as "twenty-four feet six," "twenty feet 
two," etc.; the rainfall in inches and hundredths of an inch will be 
spelled out, as "one inch twenty- two," "three inches five," etc. 
The word "rising" or "falling," coming between the stage of water 
and the amount of rainfall, will prevent mistakes by confusing the 
tenths of a foot with the inches of rainfall. When less than one inch 
of rainfall is to be reported, the word "hundredths" should be added, 
as "seventy-four hundredths," "six hundredths," etc.. 

Messages should be filed at the telegraph office as soon as prac- 
ticable after the observation has been taken. One copy of the tele- 
gram will be given to the operator at the telegraph office and one 
copy retained by the observer. 



24 INSTRUCTIONS TO RIVER AND RAINFALL OBSERVERS. 

The following is an example of a report taken at 8 a. m., 75th 
meridian time. The river stage is above the zero of the gage and the 
ground is covered with snow. The translation follows the report: 

Clinton, Tenn., March 1, 1901. 
To Observer, 

Chattanooga, Tenn. 
Clinton cloudy twelve feet five rising one inch sixty-two snow six Jones. 

[Translation.] 

Observer, Chattanooga Address of Weather Bureau observer at Chattanooga, 

Tenn. 

Clinton Name of river station at Clinton, Tenn. 

Cloudy State of weather. 

Twelve feet five Stage of river 12.5 feet. 

Rising River rising at time of observation. 

One inch sixty-two Amount of rainfall since last observation, 1.62 inches. 

Snow six XJnmelted snow on ground 6 inches. 

Jones Name of river observer. 

The following is an example of a report taken at 2 p. ni., 75th 
meridian time. The river is below the zero of the gage and there 
has been no rain or snow. The translation follows the report. 

Helena, Ark., April 20, 1901. 
To Observer, 

Memphis, Tenn. 
Helena two p. m. clear minus two feet eight falling Brown. 

[Translation.] 

Observer, Memphis Address of Weather Bureau observer at Memphis, Tenn. 

Helena Name of river station at Helena, Ark. 

Two p. m Time of observation, 2 p. m., 75th meridian time. 

Clear State of weather. 

Minus two feet eight Stage of river, —2.8 feet, i. e., 2.8 feet below the zero 

mark on the gage. 

Falling River falling at time of observation. 

Brown Name of river observer. 

TABLE FOR CONVERTING INCHES INTO TENTHS OF A FOOT. 

If the river gage is graduated in feet and inches, the inches will be 
converted into tenths of a foot by the following table before tele- 
graphing : 

1 inch of water equals one-tenth (0.1) of a foot. 

2 inches of water equal two-tenths (0:2) of a foot. 

3 inches of water equal two-tenths (0.2) of a foot. 

4 inches of water equal three-tenths (0.3) of a foot. 

5 inches of water equal four-tenths (0.4) of a foot. 

6 inches of water equal five-tenths (0.5) of a foot. 

7 inches of water equal six-tenths (0.6) of a foot. 

8 inches of water equal seven-tenths (0.7) of a foot. 

9 inches of water equal eight- tenths (0.8) of a foot. 

10 inches of water equal eight-tenths (0.8) of a foot. 

11 inches of water equal nine-tenths (0.9) of a foot. 

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